I could be wrong, but I think you can side-load any extension locally. About 3 years ago Google made it impossible to have users click a link on your website and install that way (which some people referred to as side-loading), but I think you can still enable dev mode and side-load a downloaded file.
At least as of 2 years ago, you could go to chrome://extensions, click a "Dev Mode' toggle in the top right, and sideload a downloaded crx (I know from installing https://adnauseam.io/ every time I had to use a Chromebook, it’s banned from the webstore for adding obfuscatory privacy enhancements designed as research by Daniel C. Howe and Helen Nissenbaum to gorhill's great µBlock Origin).
